The fluid product dispensing valves, notably the metering valves for dispensing pharmaceutical products in the form of aerosol sprays are known. They generally comprise a cylindrical valve body containing a metering chamber extending between two seals, a top seal and a bottom seal, a valve stem sliding in a seal-tight manner in the metering chamber between a rest position, a dispensing position and a final bottom position, The valve body is generally fixed to the neck of a vessel containing the product to be dispensed by means of a capsule crimped onto the neck. By way of example, the application EP 0 803 449 can be cited, which describes a valve known from the prior art.
One problem that this type of valve poses relates to the volume or the quantity of the dose to be dispensed. In effect, such valves are generally used to dispense doses of pharmaceutical products, in which t e doses have to be particularly accurate and dispensed constantly. These doses have to be all the more accurate since the metering valve generally contains powder in suspension in a liquid phase comprising a liquefied propellant gas. Also, the valve has to both deliver a volume of a liquid and powder that can be repeated each time it is administered, the liquid being the vector of the powder, but also a very even quantity of powder (dry mass). It is therefore important for the valve to be able to dispense a strictly identical dose of the product throughout its use.